I. Field of the Invention
The present invention relates to home hazard detection and, more particularly, to a method and apparatus for detecting an audible hazard detector in the presence of interference.
II. Description of Related Art
Many homes and businesses contain hazard detectors such as smoke detectors and carbon monoxide detectors. Such detectors are typically purchased by consumers at the retail level and installed in their homes or businesses. When a fire or carbon monoxide is detected, these detectors typically emit a piercing siren and/or visual effect (e.g., flashing light). However, older people often have hearing or mobility difficulty and remain at a significantly increased risk of injury even if the audible alarm sounds.
Home security monitoring vendors such as Ackerman or ADT™ offer networked detectors as part of security system package. In these systems, when a smoke or carbon monoxide detector is triggered, a wireless, RF signal is transmitted from the detector to a security panel located in the home, and then the security panel alerts fire, police, or other first responders via wired or wireless communications. However, these network detectors are typically system-specific and expensive, and are not generally used for middle and low income housing.
Recently, new audible detectors have been introduced into the marketplace to allow traditional, audible hazard detectors to communicate with home security systems. Such new audible detectors identify the audible siren emitted by such detectors when a hazard condition is detected, and transmit an RF signal to the security panel, where authorities may be notified by the security panel.
One problem with such new audible detectors, however, is that they typically are not able to identify an audible hazard detector from one hazard detector when two or more hazard detectors are sounding. This is because the audible signals emitted from these hazard detectors overlap as a function of time and, further, can cause modulation of the amplitude of these signals as the signals move in and out of phase from each other. As a result, such new audible detectors may not recognize when a hazard condition is occurring, and therefore no indication is provided to the security panel to call for help.
Thus, it would be desirable to be able to detect when a hazard detector is sounding in the presence of one or more additional hazard detector sirens.